Recently, digital cameras incorporating a wireless communication function and recording media equipped with a wireless communication function have made their debut. By using these devices, an image file obtained by a digital camera can be quickly transmitted to a personal computer (to be referred to as a PC hereinafter).
However, to connect to a specific PC on a network when wirelessly connecting to a PC, information for specifying the destination PC needs to be registered in a digital camera. To solve this problem, the following digital camera has been proposed (Japanese Patent Laid-Open No. 2006-67231). More specifically, when wirelessly connecting a digital camera and PC, the digital camera is connected to the target PC via a USB cable, and pairing information for specifying the communication partner PC is set in advance in the digital camera. When the start of wireless connection is instructed, the digital camera executes advertisement to the network and establishes a wireless connection with the specific PC based on the set pairing information.
Before establishing a wireless connection, the digital camera disclosed in Japanese Patent Laid-Open No. 2006-67231 needs to be connected to a communication partner PC via a USB cable and set in advance pairing information for specifying it, resulting in poor usability.
Depending on the installed OS, the PC has a different discovery protocol used in connection processing between devices. Typical discovery protocols are UPnP (Universal Plug and Play) and Bonjour.
UPnP is a technical specification for connecting devices such as a PC, peripheral device, AV system, telephone, and household appliance in the home via a network, and providing their functions to each other. UPnP was proposed by Microsoft in 1999 and is supported by 20 or more companies including Intel. UPnP is founded on a standard technology for the Internet, and aims at operating a device by only connecting it to a network without any complicated operation or setting work.
Bonjour is a technique of automatically detecting and connecting a device on an IP network such as Ethernet or wireless LAN (Local Area Network). Bonjour has been developed as a zero configuration technology which is based on a standard protocol defined by the IETF (Internet Engineering Task Force) Zeroconf working group and has the same usability as that of Apple Talk. The Zeroconf working group requests three functions: IP addressing, naming, and service discovery. These functions are implemented as follows. In addressing, communication not involving a router is determined to be of a local network, and an IP address is automatically acquired. Naming uses a multicast DNS in which no local host name need always be set. In service discovery, a device having a function the user wants to use is searched for. Bonjour is mainly adopted in Mac OS available from Apple.
Another discovery protocol is Jini available from Sun Microsystems. In the digital camera disclosed in Japanese Patent Laid-Open No. 2006-67231, pairing information needs to be set in advance while being aware of the type of discovery protocol for each PC. Therefore, it is not easy for a user having little knowledge about the network to correctly set pairing information.
A digital camera and PC have a so-called device & control point relationship in which the digital camera provides an image file to the PC in accordance with an instruction from the PC to acquire the image file. Generally, the PC serving as the control point controls a series of operations including the start of a connection with the digital camera, image transfer, and the end of the connection. However, the user may want to transfer an image file to the PC immediately after shooting, or change the transmission destination PC depending on the type of image file. In such a case, usability would be improved if the user were able to list PCs on the network by operating the digital camera and instruct a connection with the PC he wants while holding the digital camera with his hand.